Note: Descriptions are shown in the official language in which they were submitted.
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DUAL MODE VISIBLE AND INFRARED LIGHTHEAD
BACKGROUND OF THE INVENTION
[0001] This application claims the benefit of U.S. Provisional Application
No. 60/257,184 filed December 20, 2000 entitled DUAL MODE VISIBLE
AND INFRARED LIGHTHEAD.
Field of the invention.
[0002] This invention relates to dual-mode visible and infrared lighting.
Specifically, this invention relates to a dual mode visible and infrared
lighthead for use with aircraft landing lights and searchlights, and for use
1o with other vehicles.
Description of the related art.
[0003] Aircraft generally have landing lights mounted thereon to provide
illumination during taxi, take-off, and landing when visibility is reduced by
darkness or adverse weather conditions. Landing lights may be mounted
1s in a fixed position on the aircraft; alternatively, the landing lights may
be
pivotable by drive means to extend from the aircraft when needed, and
retracted to reduce drag when not in use. Searchlights are pivotable by
drive means similar to landing lights, but include an additional capability to
rotate up to 360 degrees in a plane perpendicular to the extend-retract
2o plane. Military and law enforcement helicopters commonly use
searchlights to aim a beam of light in a desired direction to illuminate
targets.
[0004.] With the advent of infra-red based Night Vision Imaging Systems
("NVIS") for covert operations, there arose a need for landing lights and
2s searchlights that were compatible with NVIS by producing infrared light
for illuminating the selected landing and search areas while eliminating
visible light. Early NVIS-compatible landing and search lights used
infrared light filters installed over conventional visible lighting systems. A
disadvantage of early NVIS-compatible lighting systems was that the
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flight crew could not switch from visible to NVIS modes during a mission,
since the infrared filters were required to be installed and removed while
the aircraft was on the ground. This disadvantage was overcome by prior
dual mode lightheads containing both visible and infrared lighting
s elements, such as Snyder, et al. U.S. Patent No. 5,695,272. Dual mode
lightheads allow the flight crew to switch between visible and infrared
lighting modes by simply applying electrical power to either the infrared or
visible portions of the dual mode lighthead as desired.
[0005] While prior dual mode lightheads offer significant advantages over
1o early manually-installed filters, they suffer from several disadvantages.
First, replacement of failed (amps is a cumbersome and difficult process
owing to the segmented lens and filter assembly, which must be removed
then re-sealed each time a lamp is replaced. This repair frequently causes
damage to the reflectors, reducing the optical efficiency of the lighthead.
15 In addition, dual mode lightheads typically emit lower light intensity than
dedicated infrared or visible lighting systems,.since the surface area on
the lighthead available for the lighting system is divided between the
visible and infrared portions. Further, prior dual mode lightheads utilize
visible light sources coupled with infrared filters to produce the infrared
20 light, generating high temperatures within the lighthead that can limit the
fife of the light elements, lenses, and sealing materials. There is a need
for a dual mode lighthead that is easier to maintain, provides higher
intensity light output, and operates at a lower temperature to extend
lighthead component life.
25 SUMMARY OF THE INVENTION
[0006] This invention is directed to a dual mode lighthead that is easier
to re-lamp, provides improved light output, and generates less heat as
compared to prior dual mode lightheads.
[0007] Specifically, the present invention is a modular design
3o incorporating a housing, preferably a cast aluminum housing. The
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housing is designed to accommodate installation of the lighting elements
from the rear of the lighthead. This prevents contamination of the
reflector with dirt, oil, or fingerprints that can reduce the optical
efficiency
of the reflector. Installing the lighting elements from the rear also reduces
s maintenance time, since the front lens does not have to be removed and
then re-sealed.
[0008] Replacement of prior front-mounted halogen lamps involves
grasping the glass envelope of the lamp to install it into a socket.
Because the presence of contaminating agents such as dirt, oil and
1o fingerprints on the lamp's glass envelope can reduce the life of the lamp,
maintenance personnel must use cotfion gloves or other protective
materials when replacing lamps. The present invention utilizes a visible
light source that includes a base that allows maintenance personnel to
handle and install the lamp from the rear of the lighthead without
is touching or otherwise contaminating the glass envelope. Further, the
lamp base allows the visible light source to be easily installed and
removed without the need for tools.
(0009) The invention also utilizes high intensity infrared diodes in
contrast to the filtered visible light sources used in prior lightheads. High
2o intensity infrared diodes offer increased infrared light emission along
with
higher efficiency, reduced power consumption, longer life, and reduced
heat generation. The high intensity infrared diodes also facilitate faster
and simpler replacement due to their modular design.
[0010] The present invention comprises a dual mode lighthead,
25 comprising: a housing comprising front, rear, top, and bottom sectors; an
attachment point connected with one of said sectors of said housing to
connect the dual mode lighthead with means for positioning the lighthead;
means for reflecting light mounted inside said housing, said means
positioned to reflect light from the front sector of said housing; at least
30 one high intensity infrared diode, said diode being installed into said
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housing from the rear sector of said housii-ig and positioned to emit
infrared light out of the front sector of said housing; at least one visible
light source, said visible light source being installed into said housing from
the rear sector of said housing such that said visible light source projects
through said reflectors and emits light from the front sector of said
housing; and at least one lens affixed to the front sector of said housing
through which one of emitted visible and infrared light passes.
[0011 ) These and other features will become better understood with
reference to the following description, appended claims, and
1o accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012) Figures 1-a and 1-b are views of the back and cover of the dual
mode lighthead,
Figure 2 is a view of the visible light source,
Figure 3 is a view of the front of the dual mode lighthead, and
Figure 4 is an electrical schematic of the dual mode lighthead.
DETAILED DESCRIPTION OF THE INVENTION
[0013) A view of the back side of the dual mode lighthead 100 is shown
in Figure 1. Dual mode lighthead 100 includes a housing 102 having a
rear sector 128, a top sector 124, and a bottom sector 126. Housing
102 also includes a front sector 122, shown in Figure 3 and discussed
below. Housing 102 is comprised of a cast or machined material,
preferably aluminum, and may optionally include a plurality of cooling fins
104 to aid in the dispersion of heat generated by the light sources.
Housing 102 further includes the parabolic reflector cavities 106 shaped
to optimize the optical design for the visible light portion of lighthead 100
wherein the visible light is emitted from the front sector 122 of housing
102. Lamp retainer slots 130 are cast or machined into the reflector
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cavities 106 to facilitate installation of the'visible light sources 200,
discussed in greater detail below. Cavities 106 may also optionally
include a plurality of heat-sink ribs 108 to help carry away heat generated
by the visible light sources. The openings 1 10 accommodate the infrared
light sources, and the openings 112 accommodate the visible light
sources of lighthead 100. An attachment point 114 is affixed to the
bottom sector 126 of housing 102 and facilitates mounting of lighthead
100 directly to the aircraft structure, or optionally to the pivot means of a
landing light or searchlight. A rear cover 1 16 protects the interior of
lighthead 100 from the elements, being secured with a plurality of screws
1 18 to the receptacles 120.
[0014] The visible light source 200 is shown in Figure 2. An
incandescent lamp 202, preferably halogen, is affixed to a lamp base
204. The lamp base 204 provides a convenient surface for handling the
~5 visible light source 200 without contaminating the lamp 202. One or
more retaining springs 206 are attached to the lamp base 204 by
conventional means such as rivets 208. The lamp leads 210 facilitate
connection of electrical power to the lamp 202.
[0015] The front of lighthead 100 is shown in Figure 3. Referring to
2o Figures 1, 2 and 3, the infrared light sources 302, preferably high
intensity infrared diodes, are installed into openings 1 10 from the rear
sector 128 of housing 102 and facing toward the front sector 122. The
visible light sources 200, preferably halogen (amps, are installed into
openings 112 from the rear sector 128 of housing 102 and facing toward
25 the front sector 122 of housing 102. As each visible light source 200 is
pressed through an opening 112 of housing 102, the retaining springs
206 spread and then snap into the lamp retainer slots 130, firmly holding
the visible light source 200 in place. The cast aluminum reflectors 306
are installed into cavities 106 to optimize light emission from visible light
3o sources 200. The lenses 308 are installed onto the front sector 122 of
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housing 102 and sealed to protect the interior of lighthead 100 from the
elements. The attachment point 1 14 is affixed to the bottom sector 126
of housing 102 and facilitates mounting of lighthead 100 directly to the
aircraft structure, or optionally to the pivot mechanism of a landing light
s or searchlight.
[0016] As shown in Figure 4, electrical power for the dual mode
lighthead is supplied by the power input lines 416, 418. Electrical power
is controlled by a switch 402, which provides logical electrical input
signals to the logic circuit 410 of the control circuit 400 via the logic
lines
420, 422. If logic circuit 410 detects the presence of an electrical
voltage on the "visible" logic line 420, the electronic switch 412, such as
a power metal oxide semiconductor field effect transistor 1MOSFET), is
activated, causing the visible light sources 200 to emit visible light. If
logic circuit 410 detects the presence of an electrical voltage on the
1s "NVIS" logic line 422, the driver control 414 activates the driver 408.
The driver 408, such as an electrical current limiter, supplies a controlled
amount of electrical current to the infrared light sources 302, causing the
infrared light sources 302 to emit infrared light. The logic circuit 410
turns off both the visible light sources 200 and the infrared light sources
302 when no voltage is detected on either of the logic lines 420, 422.
The logic circuit 410 also turns off both the visible light sources 200 and
the infrared light sources 302 if an illegal logic condition exists, such as
voltage present on both logic lines 420, 422. The high-voltage protection
filter 404 isolates electrical noise between the aircraft and the control
2s circuit 400. The power supply 406, such as a voltage regulator,
conditions the power from the aircraft to a voltage level suitable for the
components in control circuit 400.
[0017] In operation, the dual mode lighthead is mounted to a fixed or
retractable landing light mechanism, or a searchlight mechanism. A
3o control switch 402, located in the cockpit, is typically in the "Off"
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position causing electrical power to be removed from both the visible
lamps 200 and the infrared light sources 302. When the operator sets
control switch 402 to the "visible" position, electronic switch 412 is
activated, applying power to the visible light sources 200 and causing
them to emit a bright visible light. If the operator places switch 402 in
the "NVIS" position, driver 408 is actuated, causing the infrared light
sources 302 to emit infrared light to facilitate searching, targeting, and
landing during covert operations.
[0018] Although the present invention has been shown and described
1o herein with reference fio a particular embodiment for a particular
application, the present invention is not limited to aviation uses. Indeed,
the present invention is immediately applicable to hand-held and
stationary fixtures as well as all types of vehicular traffic, including
automotive, marine, and railroad.
